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811.
Effects of Alkyl Chain Length and Hydrogen Bonds on the Cooperative Self‐Assembly of 2‐Thienyl‐Type Diarylethenes at a Liquid/Highly Oriented Pyrolytic Graphite (HOPG) Interface
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Soichi Yokoyama Dr. Takashi Hirose Prof. Kenji Matsuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13569-13576
An appropriate understanding of the process of self‐assembly is of critical importance to tailor nanostructured order on 2D surfaces with functional molecules. Photochromic compounds are promising candidates for building blocks of advanced photoresponsive surfaces. To investigate the relationship between molecular structure and the mechanism of ordering formation, 2‐thienyl‐type diarylethenes with various lengths of alkyl side chains linked through an amide or ester group were synthesized. Their self‐assemblies at a liquid/solid interface were investigated by scanning tunneling microscopy (STM). The concentration dependence of the surface coverage was analyzed by using a cooperative model for a 2D surface based on two characteristic parameters: the nucleation equilibrium constant (Kn) and the elongation equilibrium constant (Ke). The following conclusions can be drawn. 1) The concentration at which a stable 2D molecular ordering is observed by STM exponentially decreases with increasing length of the alkyl chain. 2) Compounds bearing amide groups have higher degrees of cooperativity in self‐assembly on 2D surfaces (i.e., σ, which is defined as Kn/Ke) than compounds with ester groups. 3) The self‐assembly process of the open‐ring isomer of an ester derivative is close to isodesmic, whereas that of the closed‐ring isomer is cooperative because of the difference in equilibrium constants for the nucleation step (i.e., Kn) between the two isomers. 相似文献
812.
Perfluoroalkyl and ‐aryl Zinc Ate Complexes: Generation,Reactivity, and Synthetic Application
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Dr. Xuan Wang Dr. Keiichi Hirano Daisuke Kurauchi Hisano Kato Naoyuki Toriumi Dr. Ryo Takita Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):10993-10996
A combination of dimethylzinc, perfluoroalkyl iodide, and LiCl afforded a new type of perfluoroalkyl (RF) zinc ate complex. These complexes show much greater thermal stability than conventional perfluorinated metal species, such as RF–lithium species and Grignard reagents, and they can be used at room temperature or higher. The results of DFT calculations on the origin of the enhanced stability are reported and the synthetic utility of RF‐zincate complexes is demonstrated. 相似文献
813.
Synthesis of 6‐Aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles by the Cu‐Catalyzed Reaction of 2‐(2‐Bromophenyl)‐1H‐indoles with CH2(CN)2
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Kazuhiro Kobayashi Kosuke Ezaki Daisuke Hanioka Ippei Nozawa 《Helvetica chimica acta》2015,98(2):179-183
A series of 6‐aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles 4 have been prepared by treatment of 2‐(2‐bromophenyl)‐1H‐indoles 1 , available from 1‐(2‐bromophenyl)ethanones or 1‐(2‐bromophenyl)propan‐1‐ones by using Fischer indole synthesis, with propanedinitrile in the presence of a catalytic amount of CuBr and an excess of K2CO3 in DMSO at 100°. 相似文献
814.
Highly E‐Selective and Enantioselective Michael Addition to Electron‐Deficient Internal Alkynes Under Chiral Iminophosphorane Catalysis
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Dr. Daisuke Uraguchi Kohei Yamada Prof. Dr. Takashi Ooi 《Angewandte Chemie (International ed. in English)》2015,54(34):9954-9957
A highly E‐selective and enantioselective conjugate addition of 2‐benzyloxythiazol‐5(4H)‐ones to β‐substituted alkynyl N‐acyl pyrazoles is achieved under the catalysis of a P‐spiro chiral iminophosphorane. Simultaneous control of the newly generated central chirality and olefin geometry is possible with a wide array of the alkynyl Michael acceptors possessing different aromatic and aliphatic β‐substituents, as well as the various α‐amino acid‐derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active α‐amino acids bearing a geometrically defined trisubstituted olefinic component at the α‐position. 相似文献
815.
Yue Wang Koki Ogasahara Daisuke Tomihama Dr. Radomir Mysliborski Dr. Masatoshi Ishida Yongseok Hong Yusuke Notsuka Prof. Dr. Yoshihisa Yamaoka Tomotaka Murayama Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama Dr. Shigeki Mori Dr. Yuhsuke Yasutake Prof. Dr. Susumu Fukatsu Prof. Dr. Dongho Kim Prof. Dr. Hiroyuki Furuta 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16295-16300
The synthesis of organometallic complexes of modified 26π-conjugated hexaphyrins with absorption and emission capabilities in the third near-infrared region (NIR-III) is described. Symmetry alteration of the frontier molecular orbitals (MOs) of bis-PdII and bis-PtII complexes of hexaphyrin via N-confusion modification led to substantial metal dπ–pπ interactions. This MO mixing, in turn, resulted in a significantly narrower HOMO–LUMO energy gap. A remarkable long-wavelength shift of the lowest S0→S1 absorption beyond 1700 nm was achieved with the bis-PtII complex, t -Pt2-3 . The emergence of photoacoustic (PA) signals maximized at 1700 nm makes t -Pt2-3 potentially useful as a NIR-III PA contrast agent. The rigid bis-PdII complexes, t -Pd2-3 and c -Pd2-3 , are rare examples of NIR emitters beyond 1500 nm. The current study provides new insight into the design of stable, expanded porphyrinic dyes possessing NIR-III-emissive and photoacoustic-response capabilities. 相似文献
816.
Tatsunori Shibuya Dai Yoshitomi Daisuke Satoh Kazuyuki Sakaue Masahito Tanaka Hideyuki Takada Hiroshi Ogawa Kenji Torizuka Yohei Kobayashi Ryunosuke Kuroda 《Surface and interface analysis : SIA》2020,52(12):1145-1149
Biodegradable polymers such as poly-l -lactic acid (PLLA) are essential tools for a wide range of medical applications because of their mechanical robustness and bio-affinity. Laser processing is commonly used to construct various structures from biodegradable polymers. However, in general, polymers deteriorate rapidly owing to laser-induced heating effects. In this study, we investigate the optimum irradiation conditions for PLLA processing, using an ultrafast laser and finely controlling the pulse duration over the femtosecond-to-picosecond range. We report on the morphological characteristics of the craters generated by single-shot and multiple-shot laser irradiation under pulse duration control. Our results show that crater morphology and damage threshold in the single-shot regime depend on pulse duration and that the degree of crater unevenness is insensitive to pulse duration in the multishot regime. 相似文献
817.
Akihiro Sasoh Tatsuya Harasaki Takuya Kitamura Daisuke Takagi Shigeyoshi Ito Atsushi Matsuda Kouji Nagata Yasuhiko Sakai 《Shock Waves》2014,24(5):489-500
When a shock wave ejected from the exit of a 5.4-mm inner diameter, stainless steel tube propagated through grid turbulence across a distance of 215 mm, which is 5–15 times larger than its integral length scale \(L_{u}\) , and was normally incident onto a flat surface; the peak value of post-shock overpressure, \(\Delta P_{\mathrm{peak}}\) , at a shock Mach number of 1.0009 on the flat surface experienced a standard deviation of up to about 9 % of its ensemble average. This value was more than 40 times larger than the dynamic pressure fluctuation corresponding to the maximum value of the root-mean-square velocity fluctuation, \(u^{\prime }= 1.2~\hbox {m}/\hbox {s}\) . By varying \(u^{\prime }\) and \(L_{u}\) , the statistical behavior of \(\Delta P_{\mathrm{peak}}\) was obtained after at least 500 runs were performed for each condition. The standard deviation of \(\Delta P_{\mathrm{peak}}\) due to the turbulence was almost proportional to \(u^{{\prime }}\) . Although the overpressure modulations at two points 200 mm apart were independent of each other, we observed a weak positive correlation between the peak overpressure difference and the relative arrival time difference. 相似文献
818.
A small-sized sonochemical reactor in which the absolute value of the sound pressure amplitude can be estimated from the vibration velocity of the transducer was investigated. The sound pressure distribution in the reactor and the relationship between the vibration velocity and the sound pressure amplitude were derived through Helmholtz wave equation. The reactor consists of a bolt-clamped Langevin transducer and a rectangular cell with a tungsten reflector. A 3λ/4-standing-wave-field was generated in the reactor to simplify the sound pressure distribution. The sound pressure distribution was measured from the optical refractive index change of water using a laser interferometer. The experimental and theoretical results showed a good agreement in the absolute value of the sound pressure amplitude, and it was confirmed that the sound pressure in the sonochemical reactor can be estimated from the input current of the vibrator. 相似文献
819.
Satoru Ishizuka Toshiyuki Yamashita Daisuke Shimokuri 《Proceedings of the Combustion Institute》2013,34(1):745-753
Enhancement of flame speed in vortex ring combustion has been investigated experimentally. The flame speed and the maximum tangential velocity for each vortex ring were simultaneously measured with a PIV system and a high speed camera. To vary the extent of the enhancement, methane/hydrogen mixtures were used. Furthermore, rich mixtures were used as a source of vortex ring so that the situation of the experiment and the results could be applied more directly to practical use. Results have confirmed that enhancement of flame speed does occur in vortex ring combustion of rich methane/hydrogen mixtures in air. The extent of the enhancement becomes larger as the hydrogen content is increased. The flame speed reaches about twice as high as the maximum tangential velocity for pure hydrogen. Based on momentum conservation across the flame, a simple equation on the ratio of the flame speed to the maximum tangential velocity has been obtained, which has shown that the flame speed enhancement can be explained successfully by considering the spherically expanding type premixed combustion behind the flame. The pressure rise of a spherically expanding type premixed flame can explain the flame speed enhancement observed in the present rich methane/hydrogen vortex ring combustion. 相似文献
820.
Daisuke Iida Yasunari Kondo Mihoko Sowa Toru Sugiyama Motoaki Iwaya Tetsuya Takeuchi Satoshi Kamiyama Isamu Akasaki 《固体物理学:研究快报》2013,7(3):211-214
Strain relaxation in a GaInN/GaN heterostructure is analyzed by combining in situ X‐ray diffraction (XRD) monitoring and ex situ observations. Two different characteristic thicknesses of GaInN films are defined by the evolution of in situ XRD from the full width at half‐maximum of symmetric (0002) diffraction as a function of GaInN thickness. This in situ XRD measurement enables to clearly observe the critical thicknesses corresponding to strain relaxation in the GaInN/GaN heterostructure caused by the formation of surface pits with bent threading dislocations and the generation of misfit dislocations on GaInN during growth. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献